Bosch RIE : Bosch RIE

Requires: Victory Mesh
Minimum Versions: Victory Mesh 1.4.7.R
The Bosch Reactive-Ion Etching process is commonly used to etch deep, nearly vertical, pillars. Silvaco's process simulator (Victory Process) can simulate the Bosch process, however it can be costly for very deep trenches. If a user is interested in the device simulation instead, Victory Mesh can be used to generate the geometrical shape directly. In this example we will show how a deep 3D Bosch RIE trench can be cut directly using solid modeling commands.
The example consists of three stages. The example begins by forming a small section at the base of the trench, followed by an offset mirror to duplicate the repetitive trench side walls. The contacts are then cut into the resulting device via the slice command.
The first stage is to create a small cuboid of silicon. This will become the substrate. The combine and splice commands are used to insert two ellipsoids inside each other and the cuboid respectively. Finally, the top is removed via the crop command to expose the buried nested ellipsoids. This gives the bottom shape of a Bosch RIE trench.
At this point in the deck there is a mini Bosch RIE trench. The top piece of this trench can be mirrored as many times as desired using the offset mirror command. This is similar to a normal mirror, but with an optional offset. In this case the sub-section above -0.45 in the vertical z-axis (-z) is mirrored.
The two regions at the top/bottom of the device are sliced to form the contacts. The tag command is the used to change the material of these newly created regions.
At this stage a valid process mesh has been produced. It is suitable for any remesh scheme. In this example the Delaunay remesh and interface refinement along the trench are demonstrated. Finally, doping is added at the contact interfaces in the silicon. The final device can then be loaded into Victory Device.